QTC

QTC is a composite made from micron-sized metallic filler particles (Silicone Rubber) mixed into an elastomeric matrix. Quantum tunnelling composite is a flexible polymer that exhibits extraordinary electrical properties. In its normal state it is a perfect insulator, but when compressed it becomes a more or less perfect conductor and able to pass very high currents.

History:

First produced in 1996, QTC is a composite material made from conductive filler particles combined with an elastomeric binder, typically silicone rubber. The unique method of combining these raw materials results in a composite which exhibits significantly different electrical properties when compared with any other electrically conductive material.

Types of QTC:

1. Elastomeric (Material: Silicone Rubber) (The particle move close together)

2. Ink / Coating Solvent or Aqueous Polymer

3. Granular Sensors

Working of Quantum tunnelling composite:

QTC usually comes in the form of pills or sheet. QTC pills are just tiny little pieces of the material. The sheets are composed of one layer of QTC, one layer of a conductive material, and a third layer of a plastic insulator. While QTC sheets switch quickly between high and low resistances, QTC pills are pressure sensitive variable resistors.

Application:

– Touch switches (sheet)
– Force/pressure sensors (pills)
– Motor speed control using force (pills)

Benefits:

• QTC is a pressure/force sensing material. It can be easily integrated into existing products to enable force sensing opportunities and solutions.
• Product surfaces can be incorporated, coated or impregnated with QTC to impart the properties of force sensing into or onto the host surface.
• QTC material can be formed or moulded into virtually any size, thickness or shape, permitting redesign of product interfaces and providing improved ergonomics, aesthetics and user comfort.
• QTC is an enabling technology which is simple and reliable to use.
• QTC material is durable – it has no moving parts to wear out.
• QTC material is mechanically strong.
• QTC material can be made to withstand extreme temperatures limits.
• QTC material is versatile, both electrically and physically e.g. Its range and sensitivity can be altered. QTC material is also intrinsically safe – the material is a contactless switch, ideal for sparkless operation.
• QTC material can be directly interfaced to standard electronic and electrical devices.
• QTC material and/or technology can be customized for customer requirements, applications and products.

PRESSURE FORMING

Material & Description

ABS

Good general purpose material, very tough yet very hard and rigid, good impact and electrical. Available in gauges from .040 to .475 with several extruded textures. Comes opaque and can be matched in custom colors.

ABS/PC

A blend or alloy of ABS and polycarbonate that thermoforms well, weathers well, good color retention, very hard, excellent impact.

ABS/PVC

Flame retardant, tough.

Acrylic

Outstanding weather resistance, excellent optics and electrical properties, poor impact, high gloss and deep luster. Available in standard gauges from .080 to over 1″. Available in clear, transparent and opaque colors.

Acrylic, cell cast

Excellent optics and hot strength, more expensive. Acrylic, continuous and extrusion cast.
Large volume use and best price, good optics.

Acrylic film

3 or 6 mil film for laminating, decorating, and weathering of extruded ABS.

DR Acrylic

Modified acrylic with higher impact properties.

Acrylic/PVC

A blend of acrylic and PVC that is a tough, chemical-resistant material that weathers well and is flame resistant. Available in custom colors.

HDPE (high-density polyethylene)

Crystalline, very tough materials, good weather resistance with UV inhibitors, resistant to many chemicals. Available in standard gauges from .040 to .500. Available in opaque custom colors. Tough and stiff. Good low temperature. Economical.

HMWPE (high molecular weight)

Excellent environmental stress crack properties, thermoforms well, good low temperature.

HIPS (high impact polystyrene)

Good general-purpose material, rigid. Available in clear but usually opaque custom colors from .030 to .350, low cost.

PVC (vinyl)

Good general-purpose material, good abrasion and chemical resistance. Available in clear but usually opaque custom colors from .030 to .125.

Expanded PVC

Stiff, light, flat, thermoformable. Available in stock colors and gauges, generally 3 and 6 mm but others also available.

PETG

Clear, higher impact than acrylic, easy to form. Available in gauges from .030 to .500.

Pressure Forming:

Pressure Forming is the method used to produce injection mold quality, high definition plastic component parts, housings and containers without the huge expense of tooling. It involves positive pressure to force the heated plastic into the mold cavity. This is called pressure thermoforming or blow forming

Pressure Forming Working Operation:

The highly versatile pressure forming process utilizes air pressure, from 20 to 150 psi, to force the heated sheet into a temperature controlled mold cavity. Vent holes are provided in the mold to exhaust the trapped air. The final part features sharp definition of intricate contours and tight radii. Textures and accurate details are built right into the tooling. Low-cost, highly aesthetic plastic parts of varying sizes are possible due to the application of air pressure, as well as more sophisticated process controls that better monitor tool and sheet temperatures while controlling material shrinkage during forming.

Types Of Molding operation:

• Positive Mold
• Negative Mold

Negative molds  have concave cavities. A positive mold has a convex shape.

Pressure Forming over Thermo Forming:

The basic advantage of Pressure Forming over Thermo forming is the cost advantage for small production items. The mould cost for thermo forming is considerably higher in comparison to pressure forming thus for a lower quantity precision job the best suitable method used is pressure forming.

Application:

Pressure forming is used to create in a wide array of plastic products used for packaging of food trays, blisters, covers, internal parts, housings equipment, bezels, bases, and spare parts for use in business machines, electronics, computers and peripherals, bio-medical applications, and instruments.

Features:

Pressure forming achieves features beyond the capabilities of vacuum forming including louvers, ribs, recessed areas, crisp details and logos.

Pressure forming is ideal for small to medium sized production runs that do not justify the high cost of injection molding dies. Additionally, because the aluminum tooling used in pressure forming has an unlimited lifecycle, due to the non-abrasive process versus injection, it saves a great deal of money over many years of continued use. Pressure form tooling usually costs less than 10% the cost of an injection tool. There is also a significant time savings (sometimes 25%) in tooling lead time. Sheet gauges .020″ – .500″ are capable of being pressure formed.